Hexitol,glucose and surcose esters of alpha-sulfo fatty acids

ABSTRACT

ESTERS OF A-SULFO FATTY ACIDS WITH MANNHOL, SORBITOL, GLUCOSE AND SUCROSE WERE PREPARED BY DIRECT ESTERIFICATION, ACID CHLORIDE, OR ALCOHLOYSIS METHODS. THE PRODUCTS ARE EASILY SOLUBLE, BIODEGRADABLE, ANIONIC SURFACE ACTIVE AGENTS WITH FOAMING, DETERGENT, EMULSIFYING AND LIME SOAP DISPERSING PROPERTIES AND EXCELLENT STABILITY OF METAL IONS AND TO ACID OR ALKALINE HYDROLYSIS.

United States Patent 3,808,200 HEXITOL, GLUCOSE AND SURCOSE ESTERS 0F oz-SULFO FATTY ACIDS Raymond G. Bistline, Jr., Philadelphia, Frank D. Smith,

Southampton, James K. Weil, North Wales, and Alexander J. Stirton, Philadelphia, Pa., assignors to the United States of America as represented by the Secretary of Agriculture No Drawing. Original application July 29, 1969, Ser. No. 845,896, now abandoned. Divided and this application Jan. 7, 1971, Ser. No. 104,774

Int. Cl. C07c 69/32 US. Cl. 260-234 R 4 Claims ABSTRACT OF THE DISCLOSURE Esters of a-sulfo fatty acids with mannitol, sorbitol, glucose and sucrose were prepared by direct esterification, acid chloride, or alcoholysis methods. The products are easily soluble, biodegradable, anionic surface active agents with foaming, detergent, emulsifying and lime soap dispersing properties and excellent stability to metal ions and to acid or alkaline hydrolysis.

A non-exclusive, irrevocable, royalty-free license in the invention herein described, throughout the world for all purposes of the United States Government, with the power to grant sublicenses for such purposes, is hereby granted to the Government of the United States of America.

This application is a division of our copending application for patent, Ser. No. 845,896, filed July 29, 1969, now abandoned.

This invention relates to esters of u-SlllfO acids with certain polyols and carbohydrates, and to their preparation and use as surface active agents.

One object of the invention is to prepare sodium salts of mono-, diand polyesters of long chain a-sulfo fatty acids with selected hexitols, aldohexoses and disaccharides.

Another object is to prepare esters of a-sulfo acids with polyols and carbohydrates which are surface active, biodegradable, easily soluble in Water, resistant to hydrolysis and useful in the formulation of solid or liquid household detergents, in soap-detergent combinations, and as surface active agents for industrial application.

According to this invention, the above objects are achieved by esterifying the selected polyol or carbohydrate with an u-SlllfO fatty acid by direct esterification, by the acid chloride method or by the alcoholysis method.

The a-sulfo acids to which our invention relates are long chain a-sulfo fatty acids of the general formula CH (OH CH(SO 'H)CO H where n is an integer from 6 to 21, inclusive, that is from a-sulfopelargonic acid to asulfolignoceric acid. The a-sulfo acid [RCH(SO H) CO H] monoor disodium salt [RCH(SO Na)CO H, RCH(SO Na)CO- Na] or methyl ester [RCH(SO Na)CO C-H may be prepared as described in the literature [A. I. Stirton. J. Am. Oil Chemists Soc., 39, 490-496 (1962)] or a commercially available product may be used. The hexitol may be se- 3,808,200 Patented Apr. 30, 1974 lected from a group of 10 stereoisomeric forms the most common of which are D-mannitol and D-glucitol:

CH2 OH CH: O 11 HO H H!) OH HO JJH HO H H C O H EC 0 H H O H H i] 0 H D-Maunitol D-Glueitol (sorbitol) The aldohexoses may be selected from a group of 16 stereoisomeric forms (D- and L-allose, altrose, glucose, mannose, gulose, idose, galactose and talose) the most common of which are glucose, mannose and galactose:

CH0 CH0 CH0 HOH HOt'JH HiJOH HOCH HOCH HOCH HCOH H OH HO H HJ'JOH H OH H OH CIHIOH HrOH JHzOH D-Glucose D-Mannose D-Galactose The disaccharide maybe selected from the 4 most common, that is sucrose, lactose, maltose and cellobiose.

In a preferred embodiment of our invention the asulfo acids are a-sulfopalmitic acid or a-sulfostearic acid, or a mixture of the two, obtained from the sulfonation of commercial stearic acid or hydrogenated tallow fatty acid. In a preferred embodiment of our invention the hexitol is D-mannitol or D-glucitol or a commercial sorbitol from the electrochemical reduction or catalytic hydrogenation of carbohydrates; the aldohexose is D-glucose (dextrose) and the disaccharide is sucrose. Further, in a preferred embodiment of our invention the sucrose ester is a monoester or predominantly monoester and the hexitol ester is preferably primarily a monoester of a primary alcohol or primarily a diester of both of the primary alcohol groups.

We have discovered that the method of preparation employed depends upon the product to be desired. The number of possible monoesters for mannitol, because of symmetry, its 3, and the number of possible diesters is 9. Sorbitol could form 6 different monoesters or 15 different diesters. Despite this we have discovered that a process in which the a-sulfo acid acts as its own esterification catalyst gives a 60% yield of the 1,6-diester as illustrated:

(1) RCHC 0111 CIHMOG Bail-1g R R CHaOgC CH8 O;Na CH OzC {3H8 OaNa H0 H H OH HO H H0 43H H OH or H 011 EC OH Hi OH CHQOZC 0 HS O3Na CHIOQC 0 HS OaNa (from D-mannltol) (from D-glucitol) 3 4 The acid chloride method, we have discovered, can be In the case of cz-SlllfO esters of an aldohexose the prod directed to give a product which is primarily the monouct from the alcoholysis of D-glucose is essentially a ester, with esterification at the primary alcohol group: monoester of a primary alcohol:

(4) H H 5 0 (2) RCHCOCI 0011140 pyridine NaOCHa HI OH 0 --D 80311 DMF-CCI R(JHCO:CH3 CoHnOa DMF HO(|3H SOaNa HCOH R R I (E 10 HO CHgOzC HS OaNa CHgOzC HS OaNa HZOQC OHS OaNa HOEH H I OH H HO CH H0 or Because of charrmg, direct esterification of sucrose with 110011 H OH an u-sulfo acid is not possible and only acid chloride and H001: HCOH alcoholysis methods were successful. From the structure CHIOH CIHQOH sttxcrose iheietagef8 posiiblfe monloesters and 28 possible (from D-mannitol) (from D-glucitol) les ca cu a 6 rom t e ormu n( n 1) 8 X 7 and 21 1 X 2 28 CHIOH 'Despite this complexity it has been possible in the case HCOH of the acid chloride method to isolate a fraction which is HO H essentiailltyi1 a monoestelr olr1 clomposed principally of monor r mar a co 0 o HJJOH 2 esesa epl y grup A (5) H OH pyridine RCHCOC1+ CuHzzOn cmozccHs O Na DMF-C 014 II SOzNa 1! CHzOH GOHgOH O ]5\ 4 0H 1 H 6\ Despite the fact that primary alcohols are more readily I esterified, some esterification at secondary alcohol groups H0 3 2 may also be possible because of the great reactivity of the I OH 0 I CHZmCC|HSO3Na acid chloride. R

j f y is method, We h fi discovered, also leads Fractions which are less water soluble are also formed primanly t0 monoesterl at p a y alcohol P 40 and these appear to be diesters and polyesters with es This is a gentler reaction and less esterification at secondt ifi ti at b h primary d secondary hydroxyl ary alcohol groups is to be expected: groups.

The alcoholysis method was found to lead to a product which was primarily a monoester With less evidence of diester and polyester formulation. From a elemental an- (3) N a OCH; 4

RCHCOZCHS COHHOQ alyses, the known greater reactivity of primary alcohol so N F groups and the structure assigned to sucrose monornyris- 3 tate [R. U. Lernieux and A. G. McInnes. Can. J. Chem., 40, 307-309 (1967)], the product is principally a mixture CHZOZCCHSOJNB CHI ICCHSO=Na of monoesters with esterification mainly at the 6' and 6- EF H OH hydroxyl groups:

CH HO H 6 H0 or J: NEOCH H OH H OH RCHCOzCH; 012E210 3F HCIIOH HCOH 5 SOlN5 CHQOH (JJH2OH onion (from D manmtol) (from D-glucitol) CH2 OH O and 6l5 C'IJHQOH AH I HO 5! no OH 4 1 2 H H0 H HO a 2 L 3'] y cmozoonsoaNa H OH H OH HOOK 5 The oz-SlllfO esters of our invention differ greatly from CH OZCCHSOzNfi corresponding esters of normal fatty acids, saturated or I unsaturated or containing hydroxyl groups such as esters R of stearic, oleic, linoleic or ricinoleic acid. The pressure of the sulfo group makes the ester an anionic rather than a nonionic surface active agent with a great change in prop- Evidence for the structural assignments shown in Equaerties and types of application. Compared to correspondtions 1-3 are elementary analyses on the products and the ing esters of normal fatty acids the a-sulfo esters are more known greater reactivity of primary compared to secondsoluble and more resistant to acid or alkaline hydrolysis. ary alcohol groups [B Reinefeld and G. Klauenberg, Diesters and polyester of a-SLIlfO acids are surface active T ens., 5, 266-270 (1968)]. and water soluble and separation of monoesters from dior polyesters may not be necessary in order to have a useful product. In contrast sucrose distearate, for example, is not sufficiently soluble in water to give evidence of surface active properties.

The a-sulfo esters of hexitols, hexoses, and disac charides prepared by the methods of our invention, and the elemental analyses are listed in Table I. Although the products in every case are not single isomers we have found that the methods of our invention lead to products of acceptable purity Some analysis for suspected impurities is possible. The sucrose esters from the alcoholysis reaction, in particular, have remarkable solubilizing properties and are able to solubilize the reactants so that complete separation is not possible except with undue loss in yield.

Disodium salt present was calculated based on comparison of infrared absorbancy ratio C=O/COO with that for known mixtures of methyl ester and disodium salt RCH(SO Na)CO Na. Methyl ester present was calculated by saponification, collection of the methanol-water distillate and comparison with reference density tables. Total sucrose, free and combined, was determined by optical rotation. These data combined with elemental analyses gave the results of Table II.

Surface active and related properties were measured on the ot-SlllfO esters of our invention and compared with reference compounds as shown in Table III.

From Table III it is evident that the u-sulfo esters of the hexitols, hexoses and disaccharides, specifically in this case the a-sulfo esters of mannitol, sorbitol, glucose and sucrose, in comparison with sodium methyl a-sulfostearate and sucrose monopalmitate, are much more water soluble and therefore more generally useful as detergents and surface active agents. The mannitol, sorbitol glucose and sucrose esters have better foaming properties than the nonionic sucrose monopalmitate and are about equal in detergency and lime soap dispersing properties.

The a-sulfo esters of our invention are easily soluble and therefore generally compatible with other detergents, surface active agents and metal salts. A standard metal ion stability test [1. C. Harris, ASTM Bull. N0. 141, 4953 (1946)] showed a-sulfo monoor diesters of mannitol or sorbitol stable, without precipitation, in the presence of Mg++, Fe++, Ni++, Cu++ and Zn++ ions. This is true also of the sucrose Ot-SUlfO esters.

The a-SlllfO esters of our invention have many unexpected and important advantages over corresponding simple fatty acid esters of polyols and carbohydrates, such as sorbitol monostearate, sorbitol distearate, glucose monostearate, and sucrose monostearate. They are much more soluble as can be seen in Table III, they have both nonionic and anionic properties, they are much more stable to acid or alkaline hydrolysis, and they are able to solubilize less soluble compounds, including other detergents and surface active agents. All of these advantages make them more generally useful by themselves or in admixture with other components under a wide variety of conditions. Stability to alkaline hydrolysis is shown in the kinetic studies of Table IV. All of the a-SUIfO esters of our invention, the mannitol and sorbitol monoand diesters, and the glucose and sucrose esters, have the advantage of stability to both acid and alkaline hydrolysis.

The ability to solubilize detergents or surface active agents or other compounds which by themselves have somewhat limited solubility makes the a-sulfo esters of our invention very useful in formulations.

Sodium methyl a-sulfostearate is a useful detergent and surface active agent but as shown in Table III it has limited solubility, only 0.2% at room temperature, and so cannot easily enter into all types of formulations, for example liquid detergent formulations. Experiments have now shown that the a-sulfo esters of our invention, at concentration, can solubilize up to 10% of sodium methyl a-sulfostearate. Other more diflicultly soluble detergents whose presence is very desirable in liquid detergent formulations can be solubilized as well, such as hydrogenated tallow alcohol sulfates.

The following examples illustrate but do not limit the nature and scope of our invention.

EXAMPLE 1.-Mannitol, DI-(a-sulfostearate Direct esterification method A heterogeneous mixture of 28 g. (0.154 mole) of D-mannitol, 22 g. (0.060 mole) of a-sulfostearic acid, and 100 ml. of benzene was stirred and heated at reflux temperature for 4 hrs. with azeotropic removal of water. The mixture was cooled, diluted with cold 95% ethanol, neutralized with 18 N sodium hydroxide and heated to C. Disodium u-sulfostearate and excess mannitol were filtered from the hot solution. After standing at 30 C., crystallized solids (37 g.) were removed, Washed, and dried, and recrystallized from absolute ethanol to give 19 g. of white solid with the analysis and properties shown in Tables I and III. Mannitol di-(a-sulfopalmitate), sorbitol di-(a-sulfopalmitate) and sorbitol di-(asulfostearate) all with the analyses and properties shown in Tables I and III, were prepared in a similar manner.

EXAMPLE 2.- Sorbitol mono-a-sulfopalmitate Acid chloride method A solution of g. of disodium a-sulfopalmitate (0.21 mole) in 400 ml. of freshly distilled thionyl chloride was heated 15 minutes at reflux temperature. Excess thionyl chloride was removed by distillation and the residue was dried to a rotary evaporator at C. and 1 mm. pressure. A solution of the acid chloride in 500 ml. of carbon tetrachloride was added dropwise a stirred mixture of 48 g. of sorbitol (0.26 mole) in ml. of dimethylformamide and 50 ml. of pyridine during 20 minutes at 60-70 C. The reaction mixture was stirred and heated a further 15 minutes, cooled, diluted with 500 ml. of 50% ethanol and neutralized, at 10 C., with 18 N sodium hydroxide. Repeated extraction with carbon tetrachloride and aqueous ethanol gave a carbon tetrachloride layer containing diand polyesters. Low temperature crystallization from the aqueous ethanol layer and removal of sorbitol and disodium a-sulfopalmitate on the basis of their insolubility to absolute ethanol gave sorbitol monou-sulfopalmitate, presumably principally a mixture of the 1- and 6-monoesters, yield 36%. Analyses and properties are shown in Tables I and III.

EXAMPLE 3.Sucrose mono oesulfostearate Acid chloride method A solution of 100 g. disodium u-sulfostearate (0.245 mole) in 400 ml. of freshly distilled thionyl chloride was refluxed for 15 minutes, excess of thionyl chloride Was removed by distillation and the residue was dried in a rotary evaporator at 100 C. and 1 mm. A solution of the acid chloride in 500 ml. of carbon tetrachloride was added dropwise to a stirred mixture of 84 g. of sucrose (0.245 mole) in 335 ml. of dimethylformamide and 44 ml. of pyridine, during 25 minutes at 6070 C. The mixture was stirred and heated a further 15 minutes, cooled, diluted with 500 ml. of 50% ethanol and neutralized, at 10 C., with 18 N sodium hydroxide. Repeated extraction with carbon tetrachloride and aqueous ethanol gave a carbon tetrachloride layer containing diand polyesters. Low temperature crystallization from the aqueous ethanol layer and removal of disodium a-sulfostearate on the basis of insolubility in absolute ethanol gave sucrose monoa-sulfostearate, presumably principally a mixture of the monoestesr of the 6', 6 and 1' primary alcohol groups. With correction for recovered disodium u-sulfostearate the yield was 45%. Sucrose mono-ot-sulfopalmitate was prepared in a similar manner. Analyses and properties of both sucrose esters are shown in Tables I and III.

7 EXAMPLE 4.-Sorbitol mono-ix-sulfostearate Alcoholysis method A carefully dried mixture of 27 g. of sorbitol (D-glucitol, 0.148 mole) and 51 g. of sodium methyl a-sulfostearate (0.127 mole) was dissolved in 100 ml. of dimethylformamide, 0.5 g. of sodium methoxide catalyst was added, and the reaction mixture was heated and stirred 4 hrs. at 85100 C. with removal of methanol. The sol vent was removed under reduced pressure, treated with boiling absolute ethanol and filtered to remove excess sorbitol and a small amount of disodium a-sulfostearate. Crystallizaiton from the filtrate at C. gave sorbitol mono-u-sulfostearate, yield 73%, purity 78% with the analysis and properties shown in Tables I, II, and III. 15

Mannitol mono-u-sulfopalmitate, sorbitol mono-a-sulfopalmitate, and mannitol mono-u-sulfostearate were prepared in a similar manner.

EXAMPLE 5.G1ucose mono-a-sulfopalmitate Alcoholysis method dissolved in 100 ml. of dimethylformamide. Sodium methoxide catalyst, 0.5 g. was added and the mixture was stirred and heated for 5 hrs. at 100 C. with removal of methanol at mm. Solvent was removed at 0.1 mm.,

and the glassy residue was heated and stirred with absolute ethanol and filtered to remove insoluble glucose and disodium a-sulfopalmitate. Crystallization from the filtrate gave glucose mono-a-sulfopalmitate, yield with the analysis and properties shown in Tables I and III. Glucose mono-a-sulfostearate was prepared in a similar manner.

EXAMPLE 6.-Sucrose mono-a-sulfopalmitate Alcoholysis method Sucrose 50 g. (10X grade, 0.146 mole) and sodium methyl oz-sulfopalmitate 50 g. (0.134 mole) were dried at 100 C. at 3 mm. pressure and dissolved in 100 ml. of dimethylformamide. Sodium methoxide catalyst, 0.5 g., was added and the mixture was heated and stirred 6 hrs. at 100 C., removing methanol at 40 mm. pressure, and finally dimethylformamide at 0.1 mm. The glassy residue was treated with hot absolute ethanol and filtered to remove insoluble sucrose and disodium a-sulfopalmitate. Crystallization from the filtrate at 20 gave sucrose mono-a-sulfopalmitate, yield 67%, with analysis and properties shown in Tables II and III. Sucrose mono-asulfostearate was prepared in a similar manner. As shown in Table II the sucrose esters from the alcoholysis reaction, because of solubilizatiion, may contain sucrose, methyl ester, and disodium salt. Further purification is possible by solution in 10% ethanol and removal of the methyl ester by overnight crystallization.

TABLE L-HEXITOL, HEXOSE AND SUCROSE ESTERS Elemental analysis, percent Found Theory Esteriflcation Esters 2 method 0 H Na 8 C H Na S 1 Sorbitol a-suliopalmitate Acid chloride 50. 54 8.88 4.43 6.37 50.56 8. 29 4.40 6.14 2. Mannitol a-suliopalmitate Alcoholysis.- 50. 38 8. 63 4. 32 6. 14 50. 56 8. 29 4. 40 6. 14 3. sorbitol a-suliopalmitate --do--- 49. 86 8. 62 4. 69 6. 00 50. 56 8. 29 4. 40 6. 14 4. Mannitol a-sulfostearate ..do 51. 24 8. 77 4. 06 5. 83 52. 34 8. 4. 18 5. 82 5. Sorbitol a-suliostearate .do 52. 08 8. 75 4. 28 5. 75 52.34 8. 60 4. 18 5. 82 6. Glucose a-sultopalmitate .do..- 49. 76 8. 19 4. 41 5. 97 50. 75 7. 94 4. 42 6. 16 7. Sucrose a-sulfopalmitate Acid chloride- 48. 7. 94 3. 53 5. 00 49. 25 7. 53 3. 37 4. 8- -do Alcoholysis---. 48. 53 7. 3. 45 4. 69 49. 25 7. 53 3. 37 4. 70 9--- Sucrose a-sulfostearate Acid chloride- 49. 65 8. 15 3. 25 4. 47 50. 69 7. 80 3. 24 4. 51 10-- -d0 Alcoholysis.- 49. 30 7. 91 3. 59 4. 47 50. 69 7. 80 3. 24 4. 51 11-- Mannitol a-sulfopalmitate Direct.-.-. 53. 06 8. 28 5. 35 7. 52. 63 8. 37 5. 33 7. 40 17-. Sorbitol a-sulfopalmltate -.do. 53. 32 8. 21 5. 19 7. 75 52. 63 8. 37 5. 33 7. 40 13-- Mannitol a-sulfostearate --do 54. 50 8. 47 4. 59 6. 62 54. 88 8. 77 5. 00 6. 98 14 Sorbitol a-suliostearate .-do 53.98 8.24 4.74 6. 96 54.88 8.77 5.00 6. 98

2 Esters 1-10 are monoesters, esters 11-14 are diesters.

TABLE IL-ANALYSIS OF ESTERS FROM THE ALCOHOLYSIS REACTION Percent Sodium methyl Disodium Monocstcr o.-sulioa-sulfo- Hexitol oi hexitol Preparation stearate stearate or sucrose or sucrose Sodium mannitol a-suliostearate 4 2 6 88 Sodium sorbitol a-sulfostearate. 12 3 7 78 Sodium sucrose a-sulfostearate 10 5 15 70 TABLE IIL-SURFACE ACTIVE PROPERTIES Lime Ca soap Solustadis- Foam Deterbility bility, persing height gency E a-Sulio ester e and reference com- Esterification 25 C ppm. power 60 0., 6 pounds b method percent CaCOa percent mm. AR

1 Sorbitol u-suliopalmitate Acid chloride 20 630 14 170 31 Mannitol a-suliostearate..-- Alcoholysis 20 1,500 10 170 32 3-. Sorbitol a-suliosterate -do... 20 650 14 180 31 4.- Mannltol a-suliostearate Direct. 20 1,800 10 27 5-. Sorbitol a-suliostearate .do..-. 20 1, 800 10 27 6-- Glucose a-suliopalmitate Alcohclysis.. 20 1, 630 8 210 34 7-. Sucrose a-suliopalmitate Acid chloride 20 1, 800 9 160 28 8-. Sucrose a-suliostearate Alcoholysis.. 2 1, 800 10 31 Sodium methyl a-sultostearate 0. 2 1,8q0 9 180 35 Sucrose monopahnitate 0.5 9 50 30 Esters #4 and #5 are diesters, all others are monocsters.

b 9 and 10 are the reference compounds.

s The 20% solutions are clear and maximum solubility may be even greater.

d Modified Earl; method, Ind. Eng. Chem. 29, 1234-1239 (1937).

0 Method of Borghetty, J. Am. Oil Chemists Soc. 27, 88-90 (1950).

1 Ross Miles test (Oil & Soap 18, 99-102 (1941) on built solutions (005% active ingredient plus 0.20% builder) in hard water of 300 p.p.m.

8 Increase in reflectance after washing standard soiled cotton in 0.25% built solutions (0.05% active ingredient pll ls 0.20% builder) in hard water of 300 p.p.m.

Commercial sample 9 10 TABLE IV.STABILITY 'IO HYDROLYSIS glucose u-sulfopalmitate- [Solutions 0.1 N with respect to NaOH and ester at 100 0.] a 0 Ti g c i 22265 5 References Cited k 13%;; hydrfil si UNITED STATES PATENTS rate t 3,632,804 1/1972 Gray et al. 260-234 R Sucrose monotalhmatgmt. 08g 10g 2%. 3 figifiiigfifigga fiieii? e JOHNNIE R. BROWN, Primary Examiner CnHuCOgCHzCHzSOaNB. 4.3 55 2.3 10 a Secona order reaction rate constant, kz=1lt z/a(z-a) lnliters per mole US X'R' per minute. 25289, 353

We claim: 1. Sodium sucrose a-sulfopalmitate. 15 

